Saw.



G. H. DOUGLAS.

SAW

APPLICATION FILED-APR, 15, 1912.

1 0 33,996. Patented July 30, 1912.

Fd'v 1,

wumssrzsi INVENTQR Specification of Letters Patent.

Patent-ed Jeri Y 3%, 11912.

Application filed April 15, 1912. Serial No. 690,892.

To all whom it may concern:

Be 1t known that 1, CHARLES H. DOUGLAS,

a citizen of the United States, and a resident of Quincy, in the countyof Branch and State of Michigan, have invented certain new and usefulImprovements in Saws, of which the following is a specification.

lvly invention relates to improvements in theteeth of saws, and theobject is to provide a saw that will out easily and accurately throughtimber of every quality and kind without-scoring or roughening the wallsof the kerf, and without consuming as much power to do a given amount ofwork as other saws. I attain this object by the form and construction ofthe saw-teeth herein described and illustrated in the accompanyingdrawings.

Figure l is a small portion of a circular saw, showing a few of theimproved teeth. Fig. 2 is an edge view of the same. Fig. 3 is anenlarged view of one tooth. 4 is a cross section through line w :0, Fig.

Similar letters refer to similar parts throughout the several views.

The teeth are formed with a clearance on the back or outer edge of eachteeth, from the point or cutting edge to the heel, of about five degreesfrom the line of the periphery of the saw blade, for the purpose ofcausing them to make easy and clean chisel cuts in the wood, and thus toavoid, as far as possible, breaking it into saw-dust. On one side ofeach tooth there is aiiat rib A, which extends from the cutting point tothe heel, and on the opposite side of each is a concave bevel B. Theseribs are on alter nate sides of the teeth and project beyond the surfaceof the blade about one hundredth of an inch at the cut-ting point, and atrifle less at the rear. The object of the ribs is to widen the cuttingpoints of the teeth and at the same time to present a flat surfaceagainst the walls of the kerf that will protect them from being scoredor roughened while sawing. The object of the bevels is to narrow thecutting points of the teeth to about half the width of the kerf. in myformer patent this bevel. was made fiat, as represented by the dottedline D in Fig. 4. and consequently the teeth were thicker at the bottomof the ribs than at the cut-ting points, and consequently entered thewood like wedges, which caused undue friction while sawing, and also hada tendency to divert the saw from a straight line. To obviate thisditlricultv, the bevel B is made concave, as shown in Fig. 4;, whichbrings that side of each tooth about parallel with the rib A to thedepth of anv chip it may cut. H

The chisel points C, are made on a slight angle, and form an acute anglewith the face of the ribs A, which gives the teeth an easier cut andbetter etl ect in cross-cutting.

In this saw invention 1 have sought to so form the teeth that they mayreach the. acme of both simplicity and perfection. In this I havesucceeded so well that in all the numerous tests that have been given*them. they saw equally Well every kind or quality of timber, b li'g sonand dry, and in everv direction through the grains, without.necessitating the least variation from the form oi? the teeth hereindescribed.

In the test of these improved saws made by the U. S. Governmentofiicials at. the Forest- Products Laboratory, it was demon strated thatthey had the follow n ooin of superiority over other saws: 1. They dovery much better surface work. 2. They require 2.o% less power. Theywaste 20% less wood in the keri'. 4. They are more rapid in sawing. 5.They can be sharpened in one-fourth the time.

Having fully described invention. what I claim and desire to secure byLetters Patent is 1.. it saw provided with teeth so that ti eir backs orouter edge. hare a sic of about fire degrees angle :5... .n theperiphery of the blade, and on the 1; of which there are ribs A A, whichor; from the cutting points to or toward the heels, and on the oppositesides more are concave bevels B, B, of such ccncavitt that the points ofthe teeth do not increase in thickness for at least a portion of theirdepth; substantially as and for the pin pose herein specified.

2A. saw tooth that is provided with rib 41, on one side, which extendsfrom the cutting point of said tooth to or toward the heel, and aconcave bevel B, on the other side, of such concavity that the point ofthe" tooth does not increase in thickness for that. portion of its depthwhich enters the wood at each cut while sawing; substantially as and forthe purpose specified.

3. A saw tooth that has in combination. a rib A on one side, a concavebevel B of such t. the line it concavity that the point ofthe to octhcloes and State of- Michigan this 11th day of not increase in thicknessfor at least a por- April A. 'D. 1912. I I

tion of its depth on the other si e and a v 'euttingpointC that is'achisel point which v CHARLES DOUGLAS v 5 is at an acute angle with theface of the rib. 'Witnesses: v r

A, substantially as herein specified. I 1 ORRIN M. BOWEN,

v Signed at Quincy in the county of Branch GREENING.

